A plasma display panel (referred to as PDP hereinafter), having the capability of finer resolution and larger screen size, is used in commercial products such as a 65-inch class television set. In recent years, a PDP has been used in so-called “full-spec” high-definition televisions, with the number of scanning lines being twice that of a display device which uses the conventional NTSC method. In addition, a lead-free PDP is demanded to deal with environmental issues.
A PDP is basically composed of a front panel and a back panel. The front panel has a glass substrate made of sodium borosilicate based glass produced by a float process. The front panel further has display electrodes, a dielectric layer, and a protective layer, each formed on one main surface of the glass substrate. A display electrode is composed of striped transparent electrodes and bus electrodes. The dielectric layer, covering the display electrodes, works as a capacitor. The protective layer, made of magnesium oxide (MgO), is formed on the dielectric layer. A bus electrode is composed of a first electrode for reducing the connection resistance and a second electrode for blocking light.
The back panel has a glass substrate; address electrodes, a base dielectric layer, barrier ribs, and a phosphor layer are each formed on one main surface of the glass substrate. The address electrodes are striped. The base dielectric layer covers the address electrodes. The barrier ribs are formed on the base dielectric layer. The phosphor layer, formed between respective barrier ribs, is composed of red, green, and blue phosphor layers, emitting red, green, and blue light, respectively.
The front panel and back panel are arranged so that the surfaces with the electrodes formed thereon face each other, and they are sealed airtight. Further, an Ne—Xe discharge gas is encapsulated in a discharge space partitioned by the barrier ribs, at a pressure of 400 Torr to 600 Torr.
The PDP discharges with an image signal voltage selectively applied to some display electrodes. Ultraviolet light generated with discharge excites each color phosphor layer. Consequently, the PDP emits red, green, and blue light to display a color image.
A bus electrode contains silver to ensure conductivity. The dielectric layer conventionally contains glass frit with a low melting point containing lead oxide as the principal component. However, a PDP containing lead-free glass frit to deal with environmental issues of recent years is disclosed in patent documents such as Japanese Patent Unexamined Publication No. 2003-128430 (patent literature 1), No. 2002-053342 (patent literature 2), and No. H09-050769 (patent literature 3).
For glass frit used when forming bus electrodes, a PDP containing bismuth oxide instead of lead is disclosed in Japanese Patent Unexamined Publication No. 2000-048645 (patent literature 4).    [Patent literature 1] Japanese Patent Unexamined Publication No. 2003-128430    [Patent literature 2] Japanese Patent Unexamined Publication No. 2002-053342    [Patent literature 3] Japanese Patent Unexamined Publication No. H09-050769    [Patent literature 4] Japanese Patent Unexamined Publication No. 2000-048645